Re: [RFC] net/bridge: port based vlan filtering for bridges

Stephen Hemminger
2012-04-11T15:38:38Z

On Wed, 11 Apr 2012 11:36:29 -0400
Benjamin LaHaise <bcrl@kvack.org> wrote:

> On Wed, Apr 11, 2012 at 08:30:52AM -0700, Stephen Hemminger wrote:
> > On Wed, 11 Apr 2012 11:10:02 -0400
> > Benjamin LaHaise <bcrl@kvack.org> wrote:
> >
> > > Hello folks,
> > >
> > > Attached is the first stab at a patch to make it possible to filter packets
> > > received from other bridge ports based on the port number. This can be used
> > > to emulate port based VLANs that some switches support.
> > >
> > > The justification for this is a bit interesting. Initially, I had been
> > > filtering packets using firewall rules. Unfortunately, the number of
> > > filter rules becomes impossible to manage when trying to filter traffic
> > > between 100 different ports. CPU overhead of the filters is also a major
> > > problem.
> > >
> > > The particular use-case I'm dealing with is simulating wireless networks
> > > on a system using LXC containers. Each guest has a veth device that is a
> > > member of the bridge, but the topology of which nodes can "hear" each other
> > > changes at runtime.
> > >
> > > Comments/thoughts?
> > >
> >
> > Nak. If firewall doesn't work then implement a better netfilter
> > module.
>
> That still results in the CPU overhead of packet duplication for each and
> every bridge port regardless of the port receiving the packet or not.
> Hmmmm, would a NF_HOOK in should_deliver be okay?

Sure. Having better way to do policy would be great. Just don't want
to have implementations of specific policies in generic code.